Emulsions
Chapter Name : Surface Chemistry |
Sub Topic Code : 102_12_05_06_01 |
Topic Name : Emulsions |
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Sub Topic Name : Emulsions |
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Introduction
We discuss what an emulsion is, its types, the role of emulsifying agents and the properties shown by emulsions.
Pre-Requisites:
Colloid, Miscible, Dispersion Medium, Centrifugation, Tyndall Effect, Brownian Effect, Precipitation, Electrolytes.
Activity:
The cream or foam in espresso coffee is actually an emulsion- made from coffee oil in water. Mayonnaise, too, is Oil in Water emulsion, and is unstable. It is stabilized using egg yolk and another emulsifier.
Real Life Question:
How do detergents work? They are a kind of emulsifying agent and stabilize the interface between oil and water.
Key Words / FlashCards
| Key Words | Definitions (pref. in our own words) |
|---|---|
| Emulsion | A colloid where both the components are liquids which are partially miscible or immiscible. |
| Emulsifying agent | Also called emulsifier, a substance that stabilizes an emulsion and prevents it from breaking down by forming a thin layer between the particles and medium. |
Learning aids / Gadgets
| Gadgets | How it can be used |
|---|---|
| Breaking down common emulsions | We can take household emulsions like milk and break down their components or add emulsifiers and watch what happens, to understand them. |
| Videos | Watching videos on the formation of emulsions and the action of emulsifying agents. |
Real life uses :
Emulsions are all around us, as are emulsifiers. We find them when we use detergent in the washing machine, enjoy a cold coffee, spread butter on the last piece of toast, and even when we drink bourn vita.
Places to visit :
The mayonnaise which you love? It is an emulsion too, of the Oil in Water type. It is unstable, and egg yolk is used to stabilize it. Similarly, the foam on top of your CCD espresso? Again, an emulsion made from coffee oil in water.
Practical examples around us
| Examples | Explainations |
|---|---|
| Mayonnaise | It is Oil in Water emulsion that is unstable, and is stabilized using egg yolk, a common emulsifier. |
| Espresso foam | This is also Oil in Water emulsion, made from coffee oil in water. |
| Butter | Yet another common emulsion, of the Water in Oil type. This goes to show that emulsions are all around us. |
What you learn in Theory:
The definition of an emulsion, emulsifier, their types and properties of emulsions.
What you learn in Practice:
The kinds of emulsions that we use in real life and how to stabilize unstable emulsions, such as mayonnaise.